Noninvasive imaging of c(RGD)₂‐9R as a potential delivery carrier for transfection of siRNA in malignant tumors

Abstract

The purpose of our study was to develop and evaluate a novel integrin α β -specific delivery carrier for transfection of siRNA in malignant tumors. We adopted arginine-glycine-aspartate (RGD) motif as a tissue target for specific recognition of integrin α β . A chimaeric peptide was synthesized by adding nonamer arginine residues (9-arginine [9R]) at the carboxy terminus of cyclic-RGD dimer, designated as c(RGD) -9R, to enable small interfering RNA (siRNA) binding. To test the applicability of the delivery carrier in vivo, c(RGD) -9R was labeled with radionuclide of technetium-99m. Biodistribution and γ-camera imaging studies were performed in HepG2 xenograft-bearing nude mice. As results, an optimal 10:1 molar ratio of Tc-c(RGD) -9R to siRNA was indicated by the electrophoresis on agarose gels. Tc-c(RGD) -9R/siRNA remained stable under a set of conditions in vitro. For in vivo study, tumor radioactivity uptake of Tc-c(RGD) -9R/siRNA in nude mice bearing HepG2 xenografts was significantly higher than that of control probe (P < .05). The xenografts were clearly visualized at 4 hours till 6 hours noninvasively after intravenous injection of Tc-c(RGD) -9R/siRNA, while the xenografts were not visualized at any time after injection of control probe. It was concluded that c(RGD) -9R could be an effective siRNA delivery carrier. Technetium-99m radiolabeled-delivery carrier represents a potential imaging strategy for RNAi-based therapy.

Targeted Delivery of siRNA with pH-Responsive Hybrid Gold Nanostars for Cancer Treatment

“…9R/DG-GNS (hydrazone) also showed uptake by tumor cells due to the targeting effect of DG. Positive 9R can bind the negative siRNA, used as a gene carrier [ 40 , 41 ], and it has been shown to have superior transmembrane transport ability [ 42 , 43 ]. In addition, the hydrazone bond was destroyed in the low endosomal pH microenvironment of tumor cells.…”